Polish archives of internal medicine | 2019
New data on sarcoidosis in Poland.
Abstract
POLISH ARCHIVES OF INTERNAL MEDICINE 2019; 129 (9) estimated the incidence of sarcoidosis to range from 3.8 to 4.5/100 000 and reported local dif‐ ferences in incidence rates.8 A large single ‐center study from the National Tuberculosis and Lung Diseases Research Institute, published in 2018, aimed to characterize 1810 patients hospitalized from 2010 till 2013.9 In this issue of the Polish Archives of Internal Medicine (Pol Arch Intern Med), Bogdan et al10 reports on sarcoidosis epidemiology in Poland, based on data obtained using similar methods. Their study provides important information be‐ cause they assessed nationwide data based on 23 097 patients hospitalized with the diagnosis of sarcoidosis from 2008 to 2015. The authors estimated the annual incidence rate of sarcoid‐ osis to be 7.5/100000. The 95% confidence inter‐ val was narrow (7.1–7.9), reflecting the study de‐ sign. The prevalence for the end of the studied pe‐ riod of time (2015) was estimated at 60/100 000. It should be noted that this estimation concerns the whole country population, so the prevalence rates in the most commonly affected age groups could be about twice as high. Estimations based on hospital discharge records are probably slightly underrated, because some patients with sarcoid‐ osis might not have been hospitalized for some reasons (eg, lack of consent to a hospitalization or an invasive diagnostic procedure). However, knowing the Polish healthcare settings, the num‐ ber of such patients is most probably small. The incidence rate reported by Bogdan et al10 is higher than that reported by previous local stud‐ ies.8,11 However, this reflects regional differenc‐ es rather than the increasing disease incidence, because Bogdan et al10 did not observe a signifi‐ cant increase in the number of hospitalizations due to sarcoidosis throughout the study period (2008–2015). A higher proportion of men (54.7%) is consistent with some recent findings from Po‐ land and other countries,9,12 which is in contrast to a widespread opinion that sarcoidosis is more common among women.2 The mean age of hos‐ pitalized patients was about 45 years; howev‐ er, this measure is not informative because of Sarcoidosis is a multiorgan inflammatory disease, characterized by granuloma formation in the af‐ fected organs.1 The disease most commonly in‐ volves the respiratory system, although various other sites are often affected.2 Sarcoidosis usual‐ ly remits spontaneously; however, in some cas‐ es, it leads to significant pulmonary fibrosis and impairment of lung function, or it can be life‐ ‐threatening due to central nervous system or cardiac involvement.3 Despite extensive studies, the etiology of sarcoidosis remains unknown. The genetic and environmental traits have been reported, and the most common hypothesis sug‐ gests that an environmental trigger (possibly my‐ cobacteria, propionibacteria, or other organic and inorganic substances) provokes a specific response in susceptible individuals.2 However, there is no firm evidence to support this concept. There are considerable differences in report‐ ed data on the prevalence of sarcoidosis, with the rates ranging from less than 4/100 000 to more than 140/100 000.4 Moreover, the preva‐ lence varies across countries and races. In general, papers from the United States and Scandinavian countries report higher prevalence and suggest that sarcoidosis is much more common among in‐ dividuals of African ‐American origin. Also pub‐ lications from Europe differ in reported preva‐ lence, with estimations ranging from 5.9/100 000 in Greece to more than 150/100 000 in Sweden.5,6 There is a need for actual data because the prev‐ alence of sarcoidosis has been shown to be ris‐ ing.7 Most reviews report female predominance, while recent epidemiological data have suggest‐ ed the opposite. In healthcare settings where most patients with suspected sarcoidosis are hospitalized for diagno‐ sis, hospital ‐based registry data can be used to study the epidemiology of sarcoidosis. This also holds true for the Polish healthcare system, and this methodology can provide valid estimations on disease incidence and prevalence. Indeed, some recent studies on the epidemiology of sarcoidosis in Poland have been performed using this meth‐ od. A study conducted in the Silesian Voivodeship EDITORIAL